The present invention relates generally to the control of airborne chemical contaminants and more particularly to an apparatus for removal of chemical contaminants from a waste airstream.
It will be appreciated by those skilled in the art that the control of waste byproducts of combustion and other industrial processes which produce waste airstreams has become increasingly important and difficult. For example, many municipalities and solid waste processing companies use incineration as a means for reducing the amount of solid waste. However, the process of incineration itself often produces excessive and undesirable airborne toxins and other chemical contaminants which, if not controlled and removed, would be released through a waste air stack to the atmosphere. Accordingly, a number of techniques and devices have been tried over the years in order to control these waste airstream contaminants, including inertial separation, chemical scrubbing, mechanical filtration, electrostatic precipitation, electron beam irradiation, and chemical catalytic devices. Each of these methods has achieved some success in certain applications but significant problems remain.
For example, most prior art airborne waste control systems work well on relatively large-sized particulates suspended in the airstream but are not as effective in removal of relatively fine or small particles mixed in the gas. Catalytic beds and chemical scrubbing systems are highly sensitive to precise temperature control and the gas and airborne particulates can poison the catalyst thereby reducing its effectiveness.
Electrostatic precipitation systems have been widely used to control airborne contaminants in waste airstreams. Such systems use arrays of electrodes to which is applied a high voltage so that any gas near the electrodes is ionized. Particles suspended in the gas then are charged from contact with the gas ions whereby such charged particles then migrate to an oppositely charged electrode. The accumulated particulates are then mechanically removed from the ionization chamber. These systems, however, are limited in that only solid particulate matter can be removed, they do not work on all particulate materials, and there is a significant trade off in ionization efficiency as a function of flow rate of the waste airstream through the precipitation unit.
What is needed, then, and not found in the prior art, is a waste airstream decontamination unit which is effective in removing harmful airborne contaminates regardless of their size or chemical composition and which is effective at doing so at relatively high airstream flow rates. This device is presently lacking in the prior art.